This invention relates to fuel compositions having improved low temperature characteristics. More particularly, this invention relates to compositions comprising distillate hydrocarbon fuels having minor amounts sufficient to improve cloud point, pour point and filterability of diesel and heating fuels of an additive prepared from the reaction products of long chain oligomeric alkylsuccinic anhydride or corresponding acid, a long chain mono- or polyfunctional epoxide and a long chain secondary amine.
As is well known to those skilled in the art, diesel fuels and the like present problems at low temperatures because of poor flow characteristics and clogging of fuel filters. Unmodified diesel fuels have especially poor flow characteristics at colder temperatures where wax crystal formation occurs. Consequently, there is a continuing need for more efficient means for solving these low temperature fluidity problems. The materials described herein, when added to such fuels, improve their low temperature filterability and flowability characteristics.
Although many lubricant and fuel additives have been described from various alkylsuccinic anhydrides and their esters, applicants have discovered that effective products for improving low temperature properties of diesel fuels and the like can be made from specific combinations of raw materials within a limited molecular weight range comprising an alkylsuccinic anhydride or long chain carboxylic acid or polyacid, a mono- or polyfunctional epoxide and a long chain secondary amine.
U.S. Pat. No. 4,108,613 teaches the use of a mixture of (1) the reaction product of an epoxidized alpha-olefin with a nitrogen-containing compound selected from ammonia, an amine, a polyamine or a hydroxyamine and (2) an ethylene-olefin copolymer as an additive to depress the pour point of hydrocarbonaceous fuels and oils.
U.S. Pat. No. 3,962,104 discloses lubricating oil compositions containing minor amounts of quaternary ammonium salts useful as oil improving additives wherein the quaternary ammonium salts utilize a cation derived from the reaction product of a tertiary amine with an olefin oxide and water. None of these prior art materials, however, use the specific combination of raw materials disclosed herein.
One object of this invention is to provide an additive product which will operate to lower the cloud point and the pour point of hydrocarbon fuels and improve their filterability.
A further object of this invention is to provide a convenient process for preparing these additive products.